1. Technical Field of the Invention
The present invention relates to a three dimensional information measurement method and apparatus for measuring three dimensional information on a target such as an object or a human body around the entire circumference thereof or from multiple viewpoints (multiple directions), and for inputting the measured information.
2. Description of Related Art
In the medical, apparel, or like fields, measuring three dimensional information of a target such as a human body or an object around the entire circumference thereof has been practiced for many years.
In the prior art, the following three dimensional information measurement methods have been proposed.
(1) While holding a target stationary, a distance measurement apparatus, constructed by combining a projection system and a light receiving system in one unit, is moved (turned) in a circle centered about the target with the line of sight of the apparatus being constantly directed to the object. Based on the distance information thus obtained around the entire circumference of the object, the three dimensional information of the target is computed (see, Japanese Patent Unexamined Publication No. 5-223547).
(2) While holding the distance measurement apparatus stationary, the target is moved, and its three dimensional information is computed in a manner similar to the above (see, Japanese Patent Unexamined Publication No. 5-322526). The object is placed, for example, on a rotating stage. Reference light is projected from the projection system of the distance measurement apparatus onto the target, and its reflected light is captured via a plurality of mirrors into a television camera which is the light receiving system. The distance information of the object is thus obtained around the entire circumference thereof, and based on this information, the three dimensional information is computed.
(3) There is also a method in which neither the distance measurement apparatus nor the target is rotated. In this method, distance measurement apparatuses, each constructed with a projection system paired with a light receiving system, are arranged at several locations around the target, and the distance information of the target is captured by the respective distance measurement apparatuses in a one-shot operation. Based on this distance information, the three dimensional information of the target is computed (see, Japanese Patent Unexamined Publication No. 3-138508).
However, according to the first method (1), the mechanism for moving the distance measurement apparatus becomes complex. Further, because of the necessity to stabilize apparatus operation and ensure safety, the moving speed of the distance measurement apparatus cannot be increased sufficiently. This lengthens the time required for measuring. Accordingly, when a target is a living creature such as a human being or an animal, making measurements is extremely difficult as the target tends to move during measuring.
In the second method (2) also, there are problems similar to those of the first method (1); that is, the mechanism for rotating the stage tends to increase in size and complexity, and further, the time required for measuring becomes long.
In the third method (3), the feature of being able to obtain the distance information around the entire circumference of a target in a one-shot operation solves the problems of increased complexity of the rotating mechanism and increased measuring time associated with the first two methods (1) and (2), but the need for a plurality of distance measurement apparatuses increases the cost. Further, because of the use of the plurality of distance measurement apparatuses, processing for image merging becomes necessary to integrate the three dimensional information obtained by the respective light receiving systems; this increases the complexity of processing.
The present invention has been devised in view of the above problems, and an object of the invention is to provide a three dimensional information measurement method and apparatus for measuring three dimensional information on a target around the entire circumference thereof or from multiple viewpoints at high speed using a relatively simple configuration, and for inputting the measured information.
According to one aspect of the invention, there is provide a three dimensional information measurement method for measuring three dimensional information on a target placed in an interior space of a rotator type mirror by using the rotator type mirror in combination with an imaging apparatus disposed with its light receiving axis aligned with a center axis of the rotator type mirror, comprising: projecting reference light toward the rotator type mirror from a position on the center axis, and scanning the target with mirror reflected reference light that is produced by reflecting the reference light on the rotator type mirror; and obtaining the three dimensional information of the target, based on a physical quantity corresponding to the projection angle of the reference light and on a physical quantity corresponding to the position of a projected image obtained when the mirror reflected reference light that scanned the target is captured by the imaging apparatus via the rotator type mirror.
According to another aspect of the invention, there is provided a three dimensional information measurement apparatus for measuring three dimensional information on a target placed in an interior space of a rotator type mirror by using the rotator type mirror in combination with an imaging apparatus disposed with its light receiving axis aligned with a center axis of the rotator type mirror, comprising: reference light projection means for projecting reference light toward the rotator type mirror from a position on the center axis; main scanning means for deflecting the reference light so that mirror reflected reference light, produced by reflecting the reference light on the rotator type mirror, scans the target around the circumference thereof; sub scanning means for deflecting the projection angle of the reference light so that the mirror reflected reference light scans the target in a direction parallel to the center axis; and three dimensional information computing means for obtaining the three dimensional information of the target, based on a physical quantity corresponding to the projection angle of the reference light and on a physical quantity corresponding to the position of a projected image obtained when the mirror reflected reference light that scanned the target is captured by the imaging apparatus via the rotator type mirror.
For the physical quantity corresponding to the projection angle, the projection angle itself or the physical quantity associated with the projection angle is used, such as the elapsed time from the start of the sub scan or the amount of movement of a moving mechanism used to deflect the projection angle. For the physical quantity corresponding to the position of the projected image, the distance of the position of the projected image from a reference position, the coordinates of the pixel on which the projected image is projected, or the direction opposing the pixel on which the projected image is projected, is used.
In this specification, the term xe2x80x9con the center axisxe2x80x9d includes points on the center axis and its surroundings.
The xe2x80x9crotator type mirrorxe2x80x9d used in this specification means a mirror surface or its equivalent in a shape formed by rotating a line or quadratic curve such as a parabola, hyperbola or ellipse around a generatrix or axis and includes, for example, a combination of a large number of narrow rectangular plane mirrors arranged to approximate the shape of the rotator.
According to the present invention, three dimensional information of a target can be measured for input at high speed from around the entire circumference thereof or from multiple viewpoints by using a relatively simple configuration.